Carbon Dioxide Entrained Steel

ABSTRACT

Millions of tons of steel are manufactured each year around the world. Typically gas filled void spaces within a steel matrix are not a desirable attribute in any application. With an increasing need to monitor and address carbon dioxide emissions it is desirable to utilize this by-product of current industrial processes and the internal structure of steel provides a unique place to keep carbon dioxide. 
     With the addition of carbon dioxide into the steel matrix during or before casting the final product will have altered strength characteristics, however it will also add the advantage of certain benefits such as increased strength to weight ratio for the over all steel component. Variation in gas volume and distribution will allow for a variety of new products.

CROSS REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

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REFERENCE TO SEQUENCE LISTING, A TABLE, OR COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX

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BACKGROUND OF INVENTION

Carbon Dioxide Entrained Steel is a new, useful, product of industries in need of expanded options for fabrication materials and for carbon dioxide sequestration. Using existing steel types, the percentage (by volume) of carbon dioxide containing cavities contained within the steel matrix can be carried from the current ideal of 0% or no voids to a matrix containing percentages in the 90% range (carbon dioxide-solid steel foam).

Currently, it is desirable to produce steel products without voids in uniform material matrix that promotes ductility and consistency during fabrication. The uniform nature of current steel product, also creates a uniform weight distribution. Typically steel weighs approximately 490 lbs per cubic ft of material. Although weight is not typically considered a problem any reduction in weight that could be maintained without diminishing the strength characteristics of steel would be a welcome addition in many industries.

As a result of the ubiquitous use of steel across the globe a tremendous volume of the material is produced annually. The production comes at an environmental cost as millions of tons of CO2 are released as a result of the manufacturing process for steel. The necessity for the material typically offsets this fact, but the potential of using the material production volume for carbon sequestration could alleviate some of the concern.

BRIEF SUMMARY OF INVENTION

The addition of carbon dioxide to the steel matrix serves two purposes. (1) to offset carbon dioxide emissions during the steel manufacturing process through limited carbon dioxide sequestration and (2) to increase the strength to weight ration offered by ferrous materials.

The current state of the art does not allow for voids within the steel matrix as the imperfections are considered to be defects. Carbon Dioxide entrainment creates a new type of material matrix similar to that of air entrained concrete, but with the goal of creating an alternate strength to weight ratio.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The attached drawing page illustrates the cross section of an wide flange beam, designated a “W8×67” by the American Institute for Steel Construction. The designation indicates the beam is a W or Wide flange section, it is approximately 8 inches deep, and it is 67 lbs per foot of length. The view presented is a cross section normal to the length of the beam. A W8×67 is a beam currently used I structural steel construction and was chosen as a representation of a typical steel beam cross section.

Two generic representations of void space distribution are illustrated. DWG 1A shows a cross section where the percentage of steel is higher than the percentage of carbon dioxide by volume. The second figure, DWG 1B, shows a case were there percentage of carbon dioxide by volume is higher than the percentage of steel. This case can be approximated to a foam.

DETAILED DESCRIPTION OF THE INVENTION

The addition of carbon dioxide to a steel matrix needs to occur while the steel in a molten state. Currently steel is places in a molten state before being cast into various shapes. This is a preparatory step for further fabrication steps such as hot rolling or the steel can be left in the cast condition (cast). It can also be further altered from its cast condition (cold rolled steel). Introduction of voids into the matrix after the casting process has occurred would likely degrade the steel portion of the matrix in a deleterious way.

In order to inject carbon dioxide into molten steel the steel can be tumbled in a mixer containing steel and carbon dioxide, the carbon dioxide can be injected or “aerated” in to molten steel, or the steel can be agitated with a mixing arm until a carbon dioxide rich steel had been obtained. Steel temperature and pressure can be altered to obtain the desired material mix.

Ideally the voids will be uniform in size and shape and be spaced uniformly though out the steel. However it may be beneficial to alter these variables in order to obtain a workable material. For example, a structural steel wide flange beam, used to support at building roof, may be susceptible to increased stress around its connection points to other structural members. In this case it would be beneficial to reduce the percentage of carbon dioxide entrainment at either end of the beam, while increasing the percentage at mid span. Further the stress distribution at mid span is more uniform and can require a less homogenous material.

Once the desired carbon dioxide-steel matrix has been obtained the steel can be cast, hot rolled, or cold worked in order to produce the desired type of material, ie. Structural steel, plate steel, rebar, cast parts, ect.

Special attention needs to be paid to welding, drilling, and burning the new material as the voids do not fit within current steel fabrication specifications.

The attached application stands to claim the products of manufacturer that arises from the description herein, which include; 

1) Carbon dioxide containing steel, where void spaces within the steel are filled with carbon dioxide. 2) Steel containing carbon dioxide (visually similar to a foam), where the percentage, by volume, of carbon dioxide is greater than that of the steel, within a set boundary applicable to the comparison of the two volumes. 3) The use of steel as a sequestration volume for carbon dioxide. 